A liquid crystal display device (LCD) has been widely applied to device like TV, computer, tablet computer and mobile phone, due to its advantages of small volume, low consumption, low heat, and radiation-free. In LCD, a display panel comprises an array substrate and a color film substrate which are arranged oppositely. In a peripheral region, the display panel is provided with a frame sealant for adhering the array substrate and the color film substrate and sealing a liquid crystal layer. Generally, after coating the frame sealant on the color film substrate, UV light is applied to cure the frame sealant, to complete the assembling of the array substrate and the color film substrate. The color film substrate is generally provided with a black matrix at a region corresponding to the frame sealant, and UV light cannot transmit the black matrix. Thus, it is necessary to irradiate from the array substrate side. This leads to a low curing efficiency of the frame sealant, affects the assembling effect of the array substrate and the color film substrate, and further affects the display effect and lifetime.